Valvular hemodynamics and arrhythmias with exercise following the Ross procedure.

Pulmonary autograft aortic valve replacement (Ross procedure) is increasing in popularity, particularly in children and young adults. We performed a controlled study of pediatric and adult Ross procedure patients to evaluate postoperative exercise valvular hemodynamics and cardiac rhythm. Thirty-one patients and 24 controls underwent stress echocardiography. Doppler and 2-dimensional echocardiography assessed valvular hemodynamics and right and left ventricular size at baseline and after exercise. Electrocardiography monitored cardiac rhythm. Patients and controls had neoaortic and neopulmonic valve insufficiency ranging from none to moderate that improved or did not change with exercise. Baseline and exercise mean peak transaortic gradients were not significantly different between patients (baseline 6.3 +/- 3.8 mm Hg, exercise 12.8 +/- 7.3 mm Hg) and controls (baseline 6.7 +/- 2.5 mm Hg, exercise 14.3 +/- 5.2 mm Hg). However, baseline and exercise mean peak transpulmonic gradients were significantly different between patients (baseline 20.7 +/- 9.6 mm Hg, exercise 45.2 +/- 23.5 mm Hg) and controls (baseline 3.7 +/- 1.3 mm Hg, exercise 10.6 +/- 3.7 mm Hg). Significant exercise-induced arrhythmias occurred in 8 patients (26%) and no controls. Occurrence of arrhythmias correlated with an older age at surgery and age at study. After the Ross procedure, patients have valve competence and transaortic gradients similar to controls at baseline and with exercise. However, patients have significantly increased baseline and exercise transpulmonic gradients compared with controls. Furthermore, exercise-induced arrhythmias occurred frequently in our patient group and were associated with an older age at surgery and age at study.

Effects of high-dose inhaled corticosteroids on bone metabolism in prepubertal children with asthma.

We studied the effect of inhaled corticosteroids on the increase in bone mineral content in prepubertal children with asthma. Forty-eight asthmatic, prepubertal children receiving either inhaled beclomethasone dipropionate or budesonide were evaluated. Nine children of similar age not receiving inhaled steroids served as controls. The average age of corticosteroid-treated children was 7.8 +/- 2.4 years, and of control children, 8.4 +/- 2.1 years (NS). The average dose of inhaled corticosteroids in the treated children was 0.67 +/- 0.48 mg/m(2)/day, and they were followed over a 9-20-month period. Total bone mineral content (TBMC) was measured at baseline and after 9-20 months. A derived value for 12 months' TBMC was calculated, assuming that changes in TBMC were linear with the passage of time. The change in TBMC over a 12-month period was 264 +/- 68 mg for the corticosteroid-treated children and 330 +/- 84 mg for control children (P < 0.025). In a multiple regression analysis in which adjustments were made for the effects of age, height, and weight, the change in TBMC in corticosteroid-treated children was inversely related to the inhaled steroid dose/m(2)/day (P = 0.016). The increase in the lumbar vertebral bone mineral density in control children was also significantly greater than in the corticosteroid-treated children (P < 0.025). We conclude that inhaled steroids, at an average dose of 0.67 mg/m(2)/day, when used in the treatment of asthma reduce the acquisition of bone mineral in prepubertal children.

Quantitative digital angiography as an adjunct to the intraoperative placement of endovascular stents in congenital heart disease.

Clearly identifiable intraoperative landmarks render the placement of intraoperative stents difficult. Preoperative use of quantitative digital angiography helps the surgeon accurately insert endovascular stents intraoperatively. By using defined points of reference, we were able to carefully select the size and lengths of stents before the operation and precisely place these stents in the operating room. Furthermore, we have been able to redilate these stents using the same techniques at subsequent operations. Our results reflect the efficacy of this technique.

Effects of doxorubicin on diastolic function, contractile reserve, and ventricular-vascular coupling in piglets.

The use of doxorubicin as an anticancer drug is limited by its cardiac toxicity. To examine the adverse effects of doxorubicin on cardiac function and ventricular-vascular coupling in piglets, eight piglets received five doses of intravenous doxorubicin, 1.5 mg/kg/dose, every 4-7 days starting at 3 weeks of age. A control group consisted of eight normal piglets. Using conductance and manometric catheters, indices of cardiac function, including end systolic elastance (Ees), preload-recruitable stroke work, dP/dtmax, tau, dP/dtmin, dV/dtmax, and end systolic stiffness, were calculated from volume and pressure measurements at rest and during infusion of isoproterenol. Ventricular-vascular coupling was examined by measuring arterial elastance (Ea) and Ea/Ees. Significant differences in relaxation were found between groups. Indices of diastolic stiffness and of contractile function were not different between groups. Baseline contractile efficiency was increased in the doxorubicin group. Ea and Ea/Ees were lower in the doxorubicin group. Ea/Ees was near 1 at baseline in the doxorubicin group, indicating that conditions were optimized for performance of external stroke work. Therefore, the reserve to increase external cardiac work was diminished. The finding of altered diastolic function suggests the importance of screening of diastolic indices to detect the earliest disturbances in cardiac function caused by doxorubicin.

Treatment of acute asthma: salbutamol via jet nebuliser vs spacer and metered dose inhaler.

OBJECTIVE: To compare the efficacy of salbutamol delivered by jet nebuliser (JN) with salbutamol via a pressurised metered dose inhaler (PMDI) and a large volume spacer (Volumatic) for management of acute asthma. STUDY POPULATION: A total of 160 children aged from 4 to 12 years presenting to an Emergency Department with acute asthma. METHODS: The study was of multicentre (n=5) randomised, double blind, parallel design. Children weighing less than 25 kg received salbutamol 2.5 mg via the JN or 600 microg (six puffs) from the PMDI. Children over 25 kg received salbutamol 5 mg via the JN or 1200 microg (12 puffs) via the PMDI. Clinical score (range 0-12) and PEF (over 7 years) were recorded at baseline and 15, 30, 45 and 60 mins post administration. RESULTS: The improvement from baseline at 30 min in the clinical score was 1.87 for JN and 1.43 for PMDI (P=0.09) and at 60 min was 2.15 for JN and 1.12 for PMDI (P=0.0001). The improvement in PEF at 30 min was 51 L min(-1) for JN and 27 L min(-1) for PMDI (P=0.0007) and at 60 min was 57 L min(-1) for JN and 31.5 L min(-1) for PMDI (P=0.001). CONCLUSION: Administration of salbutamol via a PMDI and a large volume spacer device provides effective relief in the management of acute asthma in children, but to a lesser extent than a jet nebuliser. This difference may represent a dose response effect.

Oral fluid therapy. A promising treatment for vasodepressor syncope.

OBJECTIVE: To investigate the predictive value of an intravenous fluid bolus during tilt table testing on clinical outcome and to evaluate of oral therapy is an effective treatment for patients with vasodepressor syncope. DESIGN: Retrospective cohort. SETTING: Regional pediatric cardiology outpatient clinic. PATIENTS: Patients (N = 58) with a positive baseline tilt table testing result who were treated with oral fluid therapy between February 1991 and March 1996. INTERVENTIONS AND MAIN OUTCOME MEASURES: Patients with a positive tilt table test result were given an intravenous bolus of isotonic saline solution. Responders were identified as having a negative tilt table test result after the bolus. Patients were prescribed a protocol of oral fluid therapy. Data were obtained from the medical record and a mailed survey. RESULTS: Of the 58 subjects, 90% had no recurrent syncope while receiving oral fluid therapy. During tilt table testing, the mean decrease in mean arterial pressure seen with symptomatic events was lower after the intravenous fluid. The heart rate, which dropped during the initial test, increased during the rests after the intravenous bolus. In the nonresponders, symptomatic episodes occurred significantly later in the tilt table test when given fluids. The response to intravenous fluid bolus had positive predictive value of 92% and negative predictive value of 11% of clinical outcome. CONCLUSIONS: Our data suggest that oral fluid therapy is an effective treatment for vasodepressor syncope in our population. Fluid bolus response during tilt table testing has a high positive but a low negative predictive value of response to oral fluid therapy. We now recommend oral fluid therapy as a primary intervention and reserve tilt table testing for oral fluid therapy failures.

Reopening after successful coil occlusion for patent ductus arteriosus.

OBJECTIVES: This study was performed to determine the frequency of patent ductus arteriosus (PDA) reopening and the factors that may predict reopening after successful coil occlusion. BACKGROUND: Transcatheter coil occlusion is a widely used and accepted method to close a PDA. After documented successful coil occlusion, we found PDAs that reopened. We hypothesized that specific factors are involved in those that reopened. METHODS: All patients who underwent percutaneous transarterial PDA coil occlusion were studied. Successful coil occlusion was documented. PDA reopening was determined when Doppler-echocardiography (DE) performed after the procedure was negative for PDA flow but at follow-up demonstrated PDA shunting. Patients with a reopened PDA were compared with all other patients in evaluating independent variables. RESULTS: Coil occlusion for PDA was attempted in 22 patients. Clinical success was achieved in 20 patients (91%), and DE was negative for PDA shunting in 19 patients (90%). At follow-up, five patients demonstrated reopening. The PDA minimal diameter was 1.4 +/- 0.5 mm (mean +/- SD) for the reopened group and 1.2 +/- 0.7 mm for the other patients. The PDA length was 2.9 +/- 1.9 mm for the reopened group and 7.1 +/- 3.2 mm for all other patients. All those with type B PDA were in the reopened group. When independent variables were compared between groups, only PDA length and type B PDA predicted reopening (p < 0.05). CONCLUSIONS: PDA reopening may occur after successful coil occlusion. Short PDA length and type B PDA are associated with reopening. The data suggest that in such anatomy, alternative strategies to the current coil occlusion technique should be considered.

Prominent venous valves in hypoplastic right hearts.

To investigate the hypothesis that embryologic abnormalities in the venous valves may be associated with abnormal cardiac development, we examined the right atrial morphologic characteristics in 20 hearts with underdevelopment of the right heart and 17 normal hearts. In the study group, 16 (80%) of the patients had significantly enlarged eustachian valves, one (5%) was slightly enlarged, and three (15%) were smaller than expected. Five (25%) had cor triatriatum dexter. In comparison, eustachian valves in the control specimens were prominent in only one (6%), normal in five (29%), and almost absent in eight (47%). The thebesian valve was also more prominent in the study cohort when compared with controls (p < 0.05). No other morphologic features of the right atrium analyzed in this study differed from those found in normal specimens. We speculate that failure of the venous valves to regress appropriately may create abnormalities in fetal circulation that predispose the fetus to maldevelopment of the right heart structures.

Left ventricular systolic function, arterial elastance, and ventricular-vascular coupling: a developmental study in piglets.

Circulatory changes occur during perinatal life that increase cardiac output and left ventricular contractile reserve. To examine postnatal changes in left ventricular systolic function and ventricular-vascular coupling, piglets underwent cardiac catheterization at 1, 2, 4, and 6 wk of age. We measured end-systolic elastance (Ees), preload-recruitable stroke work, dP/dt(max), the dP/dt(max) end-diastolic volume relation, cardiac index, heart rate, arterial elastance (Ea), and the ratio Ea/Ees, at rest, during isoproterenol infusions (0.05-1.0 microg/kg/min), and after propranolol (1 mg/kg i.v.). Resting heart rate and cardiac index decreased between 1 and 6 wk. In 1 wk olds, resting Ees was at maximum and was unchanged during isoproterenol infusion; isoproterenol increased other contractility indices. Two, 4, and 6 wk olds demonstrated reserve using all contractility indices. Contractile efficiency was not different between ages. In 1 wk olds, Ea decreased during isoproterenol infusion; isoproterenol did not change Ea at 6 wk. Ea/Ees was higher at rest at 6 wk than at 1 wk, and fell significantly on isoproterenol; isoproterenol did not change Ea/Ees at 1 wk. With beta-adrenergic stimulation, 1 wk olds increased cardiac index by increasing heart rate and decreasing afterload, 6 wk olds increased cardiac index by increasing heart rate and contractility; no change in contractile efficiency was found in either group. In summary, contractile reserve is limited at 1 wk when measured by Ees, but other indices demonstrated reserve. Indexed Ea falls in response to beta-adrenergic stimulation in all ages but 6 wk. Ventricular-vascular coupling is optimized at 1 wk even under baseline conditions.

Digital acoustic analysis of precordial innocent versus ventricular septal defect murmurs in children.

This study examines whether digital acoustic analysis of individual cardiac sound components for intensity, timing, and frequency could differentiate between innocent and pathologic murmurs. With use of this new technology, sensitive and specific criteria can be established for a fast and easy screening procedure to help differentiate between innocent and ventricular septal defect murmurs in children with suspected heart disease.

Natural course of isolated pulmonary valve stenosis in infants and children utilizing Doppler echocardiography.

Most natural history data regarding pulmonary stenosis (PS) were obtained from cardiac catheterization studies over 15 to 20 years ago. Selection bias in these studies often excluded patients with mild disease and infants. Today, Doppler echocardiography allows accurate serial assessments of stenotic lesions in patients of all ages. This study evaluates the natural history of PS utilizing serial Doppler examinations in the pediatric population. A total of 147 patients with PS and serial echocardiographic data were identified. Age at initial echocardiogram ranged from 2 days to 15 years, with a mean follow-up of 2.4 years. Sixteen of 56 patients (29%) initially evaluated within 1 month had a > or = 20 mm Hg increase in their peak systolic pressure gradient. Only 7 of 89 patients (8%) initially evaluated over 1 month had a > or = 20 mm Hg increase. Eleven of 40 newborn infants (28%) with mild obstruction had progression to moderate or severe PS compared with 10 of 68 patients (15%) initially evaluated over 1 month. Moderate PS in the newborn was also more likely to progress compared with older children. Of the 16 newborns with > or = 20 mm Hg increases, 8 developed the increase in < or = 6 months. In contrast, no patient aged >2 years whose initial gradient was <50 mm Hg developed severe PS. Mild PS may not be static, particularly in young infants. Progression in this age group occurs more often and more rapidly than in older infants and children.

Effects of commonly used adrenergic agonists on left ventricular function and systemic vascular resistance in young piglets.

This study compared the effects of high-dose infusions of various adrenergic agonists on cardiovascular function in piglets. We hypothesized that agonists would have different effects on systolic, diastolic, and vascular functions. Nine anesthetized 3-week-old piglets underwent cardiac catheterization. Manometric and conductance catheters measured pressures and volumes. Data were acquired at rest and during infusions of epinephrine, norepinephrine, dopamine, dobutamine, isoproterenol, and phenylephrine. End-systolic elastance, preload-recruitable stroke work, cardiac output, the maximum and minimum derivatives of left ventricular pressure, the relaxation constant tau, peak filling rate, and end-diastolic stiffness were obtained. Contractile efficiency and the cardiac output/pressure-volume area ratio were calculated. Regression was used for analysis of variance; p < 0.05 was considered significant. All agonists increased indexes of contractility. beta-Adrenergic agonists enhanced relaxation. Isoproterenol and dopamine increased efficiency. No drug changed diastolic stiffness. Therefore both alpha-adrenergic and beta-adrenergic agonists have inotropic effects in the 3-week-old piglet. Some beneficial effects of beta-agonists on cardiac output may be due to enhancement of relaxation and to afterload reduction. Various agents exert different effects on the cardiovascular system, and these differences may be clinically important.

New developments in the treatment of hypoplastic left heart syndrome.

Progress has been made in the treatment of children born with hypoplastic left heart syndrome. From a mortality of more than 95% at 1 month of age in an era prior to surgical intervention, an actuarial survival of 58% at 5 years of age for staged surgical palliation is now being achieved. The short-term results with cardiac transplantation also appear to be excellent. Efforts are being directed at identifying potential risk factors, and fetal ultrasonography is capable of monitoring the progression of this malformation in utero. Refinements in surgical technique and postoperative care have been achieved, reducing the overall risk of the Norwood operation and sudden hemodynamic instability in the intensive care unit. Practice patterns and perceptions of outcome vary widely. Presently there is no unanimity of opinion that surgical therapy should be offered to all patients, and comfort care continues to be a family option.

Serum lidocaine concentrations after subcutaneous administration in patients undergoing cardiac catheterization in a pediatric institution.

OBJECTIVE: We wished to determine serum lidocaine concentrations after subcutaneous injection during cardiac catheterization. METHOD: Serum lidocaine concentrations were measured in 50 patients during catheterization. RESULTS: Serum concentration was linearly related to dose per kilogram of body weight. Lidocaine concentrations were therapeutic in 38% of patients. CONCLUSION: Lidocaine dose must be considered when the drug is used for local anesthesia in children.

Population requirements for capitation planning in pediatric cardiac surgery.

OBJECTIVE: To determine the population number necessary to generate a sufficient volume of pediatric cardiac surgeries to allow accurate prediction of resource utilization. DESIGN: All pediatric cardiac surgical patients receive care in our institution by means of only four clinical pathways that are based on acuity, not diagnosis or procedure. This allows accurate tracking of resource utilization. Based on available information, 750 consecutive surgically treated patients were retrospectively assigned to a pathway. They were subsequently subdivided into study groups of decreasing sizes from 150 to 35. Variability of pathway distribution from group to group was examined as a measure of the ability to predict resource utilization based on group size. Pediatric cardiac statistics from the state of Ohio were then used to extrapolate to the population base necessary to generate each group size. SETTING: A regional pediatric cardiac referral center. PATIENTS: All sequential patients who underwent pediatric cardiac surgery between July 1991 and January 1994. RESULTS: Statewide statistics showed that a population base of 1 million people generates 100 pediatric cardiac operations. Groups of 100 patients or greater had minimal variation in pathway distribution from group to group, allowing accurate prediction of hospital charges. This was not true for groups of 50 patients or less. CONCLUSIONS: Resource utilization for pediatric cardiac surgery can be accurately predicted in a capitated setting for populations of 1 million covered lives (100 procedures) or greater. For populations of 500 000 covered lives or less, variability of case mix is great enough to suggest the need for a more individualized payment mechanism.

Anomalous course of the left main coronary artery in tetralogy of Fallot.

An extremely rare coronary artery anomaly where the left main coronary artery arose anteriorly from the right coronary sinus and coursed in front of the right ventricular outflow tract was present in a patient with tetralogy of Fallot. Preoperative angiocardiography was interpreted as normal. Operative recognition was prevented by dense adhesions and a partial intramural course. Division of the vessel at repair resulted in death of the patient. The angiographic pattern associated with this anomaly is very unusual, and in many views looks deceptively normal. Details are presented.